First, you need a sturdy tripod and ballhead. I am using the Benro A158-EX together with the Benro BH-1-M ballhead (my review here). Another piece of equipment that you will need is a remote control release. For this purpose, I have a Canon Remote switch RS-80N3. These equipment will make sure that you have shake-free images.
The tripod is necessary because you will be shooting pictures with the aperture open for a long time, so using a tripod will make sure that you will have shake-free pictures. The remote control will prevent you from touching your camera when you take your shots, thus further eliminating vibrations when you press the shutter release on the camera. (Bonus tips: if your camera has mirror lock-up, then you can use this also because the movement of the mirror before the shot can also cause vibrations in the camera. Take note that with the mirror lock up activated, the first press of the shutter flips the mirror up, then the second press of the shutter will actually take the picture. Also, if your camera has a Long Exposure Noise Reduction feature, then you can use this also.)
Now, what are the settings that you need to make very nice fireworks pictures?
If your lens comes with a lens hood, then use that to prevent any stray light from streaming into the lens. Turn off the Image Stabilization of your lens if it has one then set your ISO to 100 so that the noise from your shots will be minimal. Set your camera to Manual and start with an aperture value of f/11 and a shutter speed of 4 seconds. Set your lens to manual focus and focus at infinity. The f/11 aperture will ensure that most of the objects in your picture will be in focus while the 4 second shutter speed will enable you to catch the light trails from the fireworks. Usually, the pyrotechnic guys make a trial run of the fireworks so you will know where to point your camera for the big event. You can either use a wide angle lens to get most of the view around the fireworks or you can zoom in and focus solely on the fireworks.
You can change the shutter speed if ever your shots over- or under-expose.
Hope these tips will help your own fireworks photos. And Happy Independence Day! :)